Lumpy Investment in Regulated Natural Gas Pipelines: An Application of the Theory of the Second Best

We address investment in regulated natural gas pipelines when investment is lumpy and the demand for gas is stochastic. This is a problem that can be solved in theory as a dynamic program, but a practical solution depends on functions and parameters that are either subjective or cannot be estimated. We then reformulate the problem from the standpoint of consumers that face incomplete markets. It is shown that for reasonable parameter values consumers prefer to pay for excess capacity rather than bear the risk of congestion. These strategies can be implemented with reasonably straightforward policies. Since the demand for gas is very inelastic, the welfare losses associated from small deviations from a first best optimum are minimal. This implies that the gas pipeline system can be regulated with a relatively simple set of transparent rules without any significant loss of welfare.Transmission investment, Natural-gas regulation, Congestion management, Gas pipelines, Second-best theory

Structure and dynamics in glass-formers: predictability at large length scales

Dynamic heterogeneity in glass-formers has been related to their static structure using the concept of dynamic propensity. We re-examine this relationship by analyzing dynamical fluctuations in two atomistic glass-formers and two theoretical models. We introduce quantitative statistical indicators which show that the dynamics of individual particles cannot be predicted on the basis of the propensity, nor by any structural indicator. However, the spatial structure of the propensity field does have predictive power for the spatial correlations associated with dynamic heterogeneity. Our results suggest that the quest for a connection between static and dynamic properties of glass-formers at the particle level is vain, but they demonstrate that such connection does exist on larger length scales.Comment: 7 pages; 4 figs - Extended, clarified versio

Dynamical instabilities in density-dependent hadronic relativistic models

Unstable modes in asymmetric nuclear matter (ANM) at subsaturation densities are studied in the framework of relativistic mean-field density-dependent hadron models. The size of the instabilities that drive the system are calculated and a comparison with results obtained within the non-linear Walecka model is presented. The distillation and anti-distillation effects are discussed.Comment: 8 pages, 8 Postscript figures. Submitted for publication in Phys. Rev.

Tectonic of Proximity: Notes on the Work of Stanton Williams

[EN] The method of layering materials is the more noticeable in the work of Stanton Williams. To obtain a cohesive ensemble, they combine exposed concrete with a carefully selected stratum of ‘noble’ materials including stone, as in the Sainsbury Laboratory, or timber, as in the Britten-Pears Archive. This considered juxtaposition allows them to establish a serious dialogue between materials that enhances their inherent qualities, something that the practice indicate as fundamental to the way in which their buildings are perceived. By carving, folding and layering, Stanton Williams aim to intensify the production of a tectonic experience at multiple scales, which goes from an overall awareness of totality to a closer appreciation of details and finishes. And it is precisely this that ultimately reveals the phenomenological relationship between body, space and building, where the human experience in architecture is mediated via tectonics of proximity.[ES] El método de estratificar materiales es el más evidente en el trabajo de Stanton Williams. Para obtener un conjunto cohesivo, combinan el hormigón visto con un estrato cuidadosamente seleccionado de materiales "nobles", incluida la piedra, como en el Sainsbury Laboratory, o la madera, como en el Britten-Pears Archive. Esta considerada yuxtaposición les permite establecer un serio diálogo entre los materiales, el cual mejora sus cualidades inherentes, algo que el estudio indica como fundamental a la manera en la cual sus edificios son percibidos. Al tallar, plegar y estratificar, Stanton Williams tiene como objetivo intensificar la producción de una experiencia tectónica en múltiples escalas, que va desde una conciencia general de la totalidad hasta una apreciación más cercana de los detalles y los acabados. Y es precisamente este hecho lo que finalmente revela la relación fenomenológica entre cuerpo, espacio y construcción, donde la experiencia humana en arquitectura está mediada por la tectónica de la proximidad.Rettondini, L.; Brito, O. (2018). Tectónicas de proximidad: reflexiones acerca de la obra de Stanton Williams. EN BLANCO. Revista de Arquitectura. 10(24):5-7. doi:10.4995/eb.2018.9938SWORD57102